Effect of nonionic surfactant on micellization thermodynamics and spectroscopic profile of dye-surfactant aggregation

Abstract

Interactional study of triphenylmethane-based cationic dye i.e., basic violet-4 dye (BV) in the mixed-micellar system of two anionic surfactants viz. sodium dodecyl sulfate (NaDS) and sodium stearate (NaS) is encompassed in this manuscript. The composite micelles of nonionic surfactant triton X-100 (TX) served as better colloidal carriers to facilitate aggregation, deep penetration, and stability of dye molecules than single surfactants. The thermodynamics of the micellization was assessed conductometrically, whereas the extent of dye-surfactant interaction was quantified spectroscopically. The nonionic/anionic mixture favored micellization and lowered critical micellar concentration (CMC). Furthermore, it is observed that dye partitioning, binding, and micellization were spontaneous processes. The thermodynamic parameters including entropy, enthalpy, and Gibb’s free energy of micellization along with the determination of the CMC, degree of ionization are also explained. The parameters in terms of partition constant, partition coefficient, binding constant, Gibb’s free energy of partition, and binding were calculated from differential absorption spectroscopy. The comparative study revealed that NaDS/TX showed superior performance in dye penetration as compared to NaS/TX system.